全文获取类型
收费全文 | 4324篇 |
免费 | 803篇 |
国内免费 | 1篇 |
出版年
2022年 | 33篇 |
2021年 | 86篇 |
2020年 | 39篇 |
2019年 | 58篇 |
2018年 | 79篇 |
2017年 | 56篇 |
2016年 | 99篇 |
2015年 | 175篇 |
2014年 | 202篇 |
2013年 | 248篇 |
2012年 | 303篇 |
2011年 | 267篇 |
2010年 | 176篇 |
2009年 | 148篇 |
2008年 | 184篇 |
2007年 | 190篇 |
2006年 | 242篇 |
2005年 | 232篇 |
2004年 | 226篇 |
2003年 | 199篇 |
2002年 | 193篇 |
2001年 | 144篇 |
2000年 | 77篇 |
1999年 | 80篇 |
1998年 | 33篇 |
1997年 | 41篇 |
1996年 | 34篇 |
1995年 | 29篇 |
1994年 | 40篇 |
1992年 | 50篇 |
1991年 | 58篇 |
1990年 | 49篇 |
1989年 | 41篇 |
1988年 | 50篇 |
1987年 | 53篇 |
1986年 | 64篇 |
1985年 | 53篇 |
1984年 | 39篇 |
1983年 | 36篇 |
1981年 | 35篇 |
1980年 | 34篇 |
1979年 | 50篇 |
1977年 | 33篇 |
1976年 | 29篇 |
1975年 | 35篇 |
1974年 | 40篇 |
1973年 | 41篇 |
1972年 | 36篇 |
1971年 | 39篇 |
1969年 | 32篇 |
排序方式: 共有5128条查询结果,搜索用时 31 毫秒
1.
2.
3.
Plasma concentrations of adrenaline and noradrenaline were measured at rest from cannulated fish and following net capture. Adrenaline and noradrenaline concentrations in capture-stressed fish averaged 36,740 pmol l-1 and 38,860 pmol l-1 respectively, whereas resting values were less than 200 pmol l-1 for both amines. Erythrocyte swelling and raised blood lactate were evident in stressed fish. In vitro effects of 5 mmol l-1 adrenaline on erythrocyte suspensions suggested that the catecholamine had a direct effect on erythrocyte volume. The significance of these results is discussed in relation to the oxygen transport properties of the blood. 相似文献
4.
5.
Glutamate is the main excitatory amino acid, but its presence in the extracellular milieu has deleterious consequences. It
may induce excitotoxicity and also compete with cystine for the use of the cystine–glutamate exchanger, blocking glutathione
neosynthesis and inducing an oxidative stress-induced cell death. Both mechanisms are critical in the brain where up to 20%
of total body oxygen consumption occurs. In normal conditions, the astrocytes ensure that extracellular concentration of glutamate
is kept in the micromolar range, thanks to their coexpression of high-affinity glutamate transporters (EAATs) and glutamine
synthetase (GS). Their protective function is nevertheless sensitive to situations such as oxidative stress or inflammatory
processes. On the other hand, macrophages and microglia do not express EAATs and GS in physiological conditions and are the
principal effector cells of brain inflammation. Since the late 1990s, a number of studies have now shown that both microglia
and macrophages display inducible EAAT and GS expression, but the precise significance of this still remains poorly understood.
Brain macrophages and microglia are sister cells but yet display differences. Both are highly sensitive to their microenvironment
and can perform a variety of functions that may oppose each other. However, in the very particular environment of the healthy
brain, they are maintained in a repressed state. The aim of this review is to present the current state of knowledge on brain
macrophages and microglial cells activation, in order to help clarify their role in the regulation of glutamate under pathological
conditions as well as its outcome. 相似文献
6.
7.
8.
Summary The carbon cycle of a loblolly pine plantation in North Carolina was examined during its 12th through 16th years from planting. Net primary production during the study period averaged 2056 g C m-2 year-1. With autotrophic respiration equal to 2068 g C, the calculated gross production was 4124 g C m-2 year-1. Heterotrophic respiration of 694 g C m-2 year-1 resulted in net ecosystem production of 1362 g C m-2 year-1. In carbon cycle comparisons between forest ecosystems, autotrophic respiration rates were found to be closely coupled to regional temperature. 相似文献
9.
William A. Wells 《The Journal of cell biology》2003,162(2):168-169
10.
Sixin Jiang Brigitte Heller Vincent S. Tagliabracci Lanmin Zhai Jose M. Irimia Anna A. DePaoli-Roach Clark D. Wells Alexander V. Skurat Peter J. Roach 《The Journal of biological chemistry》2010,285(45):34960-34971
Stbd1 is a protein of previously unknown function that is most prevalent in liver and muscle, the major sites for storage of the energy reserve glycogen. The protein is predicted to contain a hydrophobic N terminus and a C-terminal CBM20 glycan binding domain. Here, we show that Stbd1 binds to glycogen in vitro and that endogenous Stbd1 locates to perinuclear compartments in cultured mouse FL83B or Rat1 cells. When overexpressed in COSM9 cells, Stbd1 concentrated at enlarged perinuclear structures, co-localized with glycogen, the late endosomal/lysosomal marker LAMP1 and the autophagy protein GABARAPL1. Mutant Stbd1 lacking the N-terminal hydrophobic segment had a diffuse distribution throughout the cell. Point mutations in the CBM20 domain did not change the perinuclear localization of Stbd1, but glycogen was no longer concentrated in this compartment. Stable overexpression of glycogen synthase in Rat1WT4 cells resulted in accumulation of glycogen as massive perinuclear deposits, where a large fraction of the detectable Stbd1 co-localized. Starvation of Rat1WT4 cells for glucose resulted in dissipation of the massive glycogen stores into numerous and much smaller glycogen deposits that retained Stbd1. In vitro, in cells, and in animal models, Stbd1 consistently tracked with glycogen. We conclude that Stbd1 is involved in glycogen metabolism by binding to glycogen and anchoring it to membranes, thereby affecting its cellular localization and its intracellular trafficking to lysosomes. 相似文献